What is the best practice, when It comes to returning a result from a query?

fun getSymbolId(symbol: String): Int {
    transaction {
        Symbols.select { Symbols.symbol eq symbol }.toList().first()
    }
}

Symbols.select { Symbols.symbol eq symbol }.first()

will be more efficient.

.toList()

will pull all results into memory, whereas

.first()

will limit 1.

I see, but it wasn't really what I was asking. What's the best practice when it comes to returning the actual result of the select?